Design and Development of High-Frequency Switching
Amplifiers Used for Smart Material Actuators With
Current Mode Control

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Abstract

This thesis presents the design and development of
two switching amplifiers used to drive the so-called
smart material actuators. Different from conventional
circuits, a smart material actuator is ordinarily a
highly capacitive load. Its capacitance is non-linear
and its strain is hysteretic with respect to its
electrical control signal. This actuator's reactive
load property usually causes a large portion of reactive
power circulating between the power amplifier and the
driven actuator, thus reduces the circuit efficiency
in a linear power amplifier scenario. In this thesis,
a switching amplifier design based on the PWM technique
is proposed to develop a highly efficient power
amplifier, and peak current mode control is proposed
to reduce the actuator's hysteretic behavior. Since
the low frequency current loop gain tends to be low
due to the circuit's capacitive load, average current
mode control is further proposed to boost the low
frequency current loop gain and improve the amplifier's
low frequency performance. Both of the circuits have
been verified by prototype design and their experimental
measurement results are given.